1. Technical Field
The invention relates to data transmission. More particularly, the invention relates to a method and apparatus for estimating channel bandwidth.
2. Description of the Prior Art
Peak and sustainable data rates achievable in mobile broadband radio access networks have evolved by three orders of magnitude over the last decade. In many cases, three generations of radio technologies co-exist in the same geography, presenting data rates from few kbps to few hundred kbps to few mbps, all supported by same mobile device and same radio access network.
In addition to static attributes that differentiate three generations of radio access technologies, such as fundamental channelization characteristics of radio interfaces, dynamic variations introduced by multi-user loading and changing propagation conditions can make the per-user perceived bandwidth vary substantially very quickly.
These dynamic variations pose challenges to any application that relies on accurate channel estimation for bandwidth and data rate calculations, particularly if the task needs to be performed at the TCP/IP level. Accurate bandwidth and data rate calculations are needed for such scenarios as streaming video, voice over IP (VOIP), quality of service (QoS) enforcement, network characterization, network tuning, load estimation, and network optimization.
Prior art approaches to bandwidth estimation include such techniques as straight averaging, in which a determination is made of bytes received over a particular time interval. Such approaches use packet trains, where an a priori known packet sequence is sent, i.e. both the sender and the receiver know about this packet sequence. One disadvantage of sending a priori packet trains is that such technique is fundamentally disruptive to the network because it takes time to make the measurement, i.e. it does not provide a real-time value of available bandwidth, and because it adds overhead to network bandwidth by consuming such bandwidth during packet train network transit time.
It would be advantageous to provide a solution to the problem of accurately estimating channel bandwidth.